The Johns Hopkins Sexually Transmitted Diseases Cooperative Research Center (JH STD CRC) is a collaborative, multidisciplinary and multi- institutional effort to conduct research on important STD pathogens and to participate in STD-related education and training at Johns Hopkins Medical Institutions (JHMI). The JH STD CRC will work in collaboration with other STD CRCs and with the STD program of the National Institutes of Allergy and Infectious Diseases to generate knowledge which can be used for the understanding, prevention and control of STDs in the United States. The JH STD CRC presents four projects and two cores. Project 1 (HPV Infections in Older Women in East Baltimore, Keeti Shah, JHMI, Project Leader) is aimed at determining if the Pap smear cervical cancer screening program in older women can be improved by inclusion of human papillomavirus DNA diagnosis as an additional screening tool. Project 2 (Early Events in Clinical Human Papillomavirus Infection, Karen Kotloff, University of Maryland, Project Leader) will investigate humoral and mucosal immune responses to HPV infections in a prospectively monitored population of undergraduate University women and will also investigate factors which might be involved in the occurrence, persistence and progression of HPV-associated cervical cytological abnormalities. Project 3 (Molecular Evolution and STD Transmission, Raphael Viscidi, JHMI. Project Leader) will identify DNA sequences of Neisseria gonorrhoeae and Chlamydia trachomatis which are associated with transmission and will then analyze if the genetic distance between infecting strains is proportional to the social distance between the infected individuals, as determined by social network measures. Project 4 (Core-Group Targeted Gonorrhoea Control in Baltimore, Jonathan Zenilman, Project Leader) will map gonorrhoea incidence in Baltimore City by the geographic information system (GIS) technology and test an intervention program for the control of gonorrhea in hyperendemic area. Epidemiology and Biostatistics (Core B, PI Dr. David Vlahov) core will serve all four projects.